Lateral rocking motion has a soothing, soporific effect on an infant. It has been proposed that gentle rocking motion stimulates the infant's prenatal recollection of the comforts of the womb. The practice of rocking an infant has its roots in pre-history with papoose slings and shoulder cradles being a part of the child rearing practices of early Eurasian and pre-Columbian cultures. In its more modern form the child's bed in the form of a cradle is slung upon pivots or mounted upon rockers. In its oldest forms the cradle was an oblong long box without a lid and originally, the rockers appear to have been detachable. However, like all other pieces of furniture, it has been subjected to changes of fashion as to its shape and decoration. Fourteenth century French miniature paintings show an infant sleeping in a tiny four-post bed slung upon arcuate rockers. In the Eighteenth century, cradles were often very elaborate, with richly carved and upholstered examples even being used for purposes of state. Later, they became lighter and simpler and eventually were replaced by the modern barred crib. In earlier times when the extended family included grandparents and many older children who were resident in the same household and when household servants were more common, there were a sufficient number of extra hands available to assist in rocking and otherwise care for the infant while his mother attended to other household chores. Modern times, however, have reduced the incidence of the extended family or servants living in the household, so that any rocking of the infant to soothe and quiet him must be shared among fewer family members and, of necessity, the amount of this beneficial service to the infant has diminished.